This invention relates to an automotive exhaust gas recirculation (EGR) system, and more particularly, to an EGR system having an electric vacuum regulator (EVR) valve and a delta pressure feedback exhaust (DPFE) sensor combined in a single assembly and mounted on the intake manifold of an internal combustion engine.
Various systems have been developed to reduce the emission of undesirable combustion products, such as nitrogen oxides (NOX), from internal combustion engines. One such system is the exhaust gas recirculation (EGR) system. In EGR systems, a portion of the engine exhaust is recirculated into the intake manifold where it mixes with incoming air. The mixture of the exhaust gases with the air-fuel mixture in the engine cylinders provides lower peak temperatures during combustion, resulting in a reduction in the quantity of NOX produced.
Known EGR systems utilize an EGR tube to divert a portion of an engine""s exhaust gases from the exhaust pipe back into the intake manifold. A schematic of a known system is shown in FIG. 1. A vacuum-operated EGR valve is arranged between the EGR tube and the intake manifold to regulate the flow of exhaust gases into the manifold. The intake manifold provides the vacuum source for operating the EGR valve. A first hose connects the manifold to an electric vacuum regulator (EVR) valve, and a second hose connects the EVR valve to the EGR valve. The EVR valve receives a control signal from the engine control unit (ECU) and regulates the amount of vacuum provided to the EGR valve, which in turn limits the flow of exhaust gases into the intake manifold.
The ECU computes the EVR control signal based on a measurement of the differential pressure of exhaust gases between two points in the EGR tube. The differential pressure reflects the amount of flow of exhaust gases in the system. The pressure measurement is obtained using a delta pressure feedback exhaust (DPFE) sensor. The DPFE sensor operates by measuring the pressure of exhaust gases at a locations on either side of a flow restriction, or orifice, in the EGR tube. The orifice and measurement locations are positioned upstream of the EGR valve. Two more hoses connect the DPFE sensor to measurement taps on the EGR tube. The DPFE continually computes a delta pressure value for the exhaust gases in the tube and provides the data to the ECU. The ECU then uses this data to compute the EVR control signal.
There are several drawbacks associated with known EGR systems. The individual sensors and actuators used in these systems each require mounting brackets, electrical connections, and input and outlet hoses. Further, the DPFE orifice and hose connections on the EGR tube require additional manufacturing steps during production of the tube. Finally, the components in proximity to the exhaust system must be made from special heat-resistant materials to allow them to withstand the heat produced by the exhaust gases. The additional, specialized parts and the added manufacturing and assembly steps result in high production costs.
The present invention provides an exhaust gas recirculation (EGR) system having an electric vacuum regulator (EVR) valve mounted contiguously with a delta pressure feedback exhaust (DPFE) sensor on a surface of the intake manifold of an internal combustion engine. The EGR system incorporating the integral EVR/DPFE sensor assembly requires fewer parts than known systems, by virtue of eliminating numerous mounting brackets, hoses, and electrical connections. Because the EVR/DPFE sensor assembly operates in a low temperature environment, no expensive heat-shielding materials are required. The EVR/DPFE sensor of the present invention utilizes only two fluid connection hoses, and a single electrical connection to the engine control unit (ECU). Further, the inventive EGR system utilizes an EGR tube without an orifice or measurement taps, thereby eliminating manufacturing and assembly steps.
In one embodiment, the EVR valve is mounted contiguously with a DPFE sensor on a surface of the intake manifold. Alternatively, the EVR/DPFE sensor assembly may be formed with a monolithic housing. A single, common port from the manifold provides a fluid connection to the EVR/DPFE sensor assembly. This connection provides a vacuum input connection to the EVR valve and the DPFE sensor.
The DPFE sensor measures a differential exhaust pressure at locations upstream and downstream of an orifice in a gasket sealing the EGR valve to the intake manifold. The upstream measurement location is in an EGR valve chamber, and the downstream location is in the intake manifold. The orifice in the inventive system, therefore, is located downstream of the EGR valve.
The present invention provides an apparatus controlling an exhaust gas recirculation valve for an internal combustion engine. The exhaust gas recirculation valve supplies exhaust gas from an exhaust pipe to vacuum in an intake manifold. The system comprises an electric vacuum regulator valve generally enclosed in a first housing, and a delta pressure feedback exhaust gas recirculation sensor generally enclosed in a second housing, the second housing contiguously engaging the first housing.
The present invention also provides an exhaust gas recirculation system for an internal combustion engine having an intake system and an exhaust system. The exhaust gas recirculation system comprises an intake manifold defining a part of the intake system; a delta pressure feedback exhaust gas recirculation sensor having a first fluid connection to the exhaust system and a second fluid connection to the intake manifold; an exhaust gas recirculation valve regulating flow of exhaust gas to the intake manifold; and an orifice in fluid communication between the intake manifold and the exhaust gas recirculation valve, the orifice having a downstream side connecting to the first fluid connection and an upstream side connecting to the second fluid connection.
The present invention further provides an exhaust gas recirculation system for an internal combustion engine having an intake system and an exhaust system. The exhaust gas recirculation system comprises an intake manifold defining a part of the intake system, and at least one of an electric vacuum regulator valve and a delta pressure feedback exhaust gas recirculation sensor being mounted on the intake manifold.
The present invention yet further provides a method of recirculating exhaust gas in an internal combustion engine having an intake system and an exhaust system. The method comprises providing an intake manifold defining a part of the intake system; providing an exhaust gas recirculation valve in a conduit connecting the exhaust system to the intake system; providing an electric vacuum regulator valve connected in fluid communication between the intake manifold and the exhaust gas recirculation valve; and providing a delta pressure feedback exhaust gas recirculation sensor measuring a differential in pressure between the intake manifold and the conduit.